Carpet or floor tiles



4, 1964 H. s. DAHLBERG ETAL 3,120,083

CARPET OR FLOOR TILES Filed April 4, 1960 4 Sheets-Sheet l TWP INVENTORSHFIROLD S. DFIHL BEFEC-i 74 i .E. Feeg gus B. QUINN flwvrm r- {MHTTOENEPS Feb. 4, 1964 H. s. DAHLBERG ETAL CARPET OR FLOOR TILES 4Sheets-Sheet 2 Mill Filed April 4, 1960 INVENTORS HAROLD S. DQHLBERGFQEIfJNCIS B. QUINN HTTORNEVS H. S. DAHLBERG ETAL Feb. 4, 1964 CARPET ORFLOOR TILES Filed April 4, 1960 4 Sheets-Sheet 3 ENTORS BERG Ul N N W &\O

I 5.=l.lE. HAROLD a DA 240 Fmwcls a. Q

@Mim, gy ATTORNEYS United States Patent 3,120,083 CET 0R FLOOR TILESHarold S. Dahlberg, Springfield, Mass, and Francis B.

Quinn, Hazardviile, Conn., assignors to Bigelow-Sanford, Inc., acorporation of Delaware Filed Apr. 4, 1960, Ser. No. 19,917 7 Claims.(Cl. 50413) The present invention relates to carpet or floor tiles andrelates, more particularly, to carpet or floor tiles which may beinstalled in interlocking relationship with a series of adjoining tiles.

An object of the present invention is to provide carpet or floor tilescomprising several layers with one of said layers forming a base havingconfigurations formed on the side edges thereof which will readilyinterlock with similar configurations on adjoining tiles in aself-aligning manner and thus, permit a series of such tiles to beinstalled by a unskilled person on a doit-yourself basis, without theuse of adhesives or nails, to form a floor covering having asubstantially continuous or uninterrupted surface.

Another object of the invention is to provide a carpet or floor tilewhich will be substantially free of raising at the edges thereof due towarping and which will readily conform to the contour of the surface onwhich it is laid.

A further object of the invention is to provide a carpet or floor tilewhich is economical to manufacture and in which the weight may be heldto a minimum so as to avoid excessive transportation expense in themarketing and distribution of the manufactured tiles.

Another object of the present invention is to provide a carpet tilecomprising several layers including a base having interlockingconfigurations formed along the side edges thereof which areself-aligning with corresponding configurations of adjoining tiles, butwhich are free from acute prominent saliencies or projections,especially at the corners of the tile, so as to minimize the possibilityof accidental damage or injury to the interlocking configurations inshipment or handling of the tiles.

Other objects and advantages of the present invention will be apparentand better understood from the following description and theaccompanying drawings, in which:

FIG. 1 is a fragmentary view in perspective of an installation of aseries of carpet tiles embodying the invention;

FIG. 2 is a fragmentary plan view from the rear of an assembly of threecarpet tiles embodying the invention;

FIG. 3 is a top plan View of a carpet tile embodying the invention;

FIG. 4- is a fragmentary view in section along line 4--4 of FIG. 3;

FIG. 5 is a fragmentary view in section similar to FIG. 4, but showinganother form of the construction embodying the present invention;

FIG. 6 is a fragmentary view in section similar to FIG. 4, but showingstill another form of tile construction embodying the present invention;

FIG. 7 is a bottom plan view of the carpet tile shown in FIG. 3, but ona smaller scale;

FIG. 8 is a section view of the base of the tile shown in FIG. 7 takenalong line '88 of FIG. 7;

FIG. 9 is a bottom plan view of the carpet tile shown in FIG. 3, but ona smaller scale and illustrating another form of base;

FIG. 10 is a section view of the base of the tile shown in FIG. 9 takenalong line 10-11i of FIG. 9.

FIG. 11 is a bottom plan view of the carpet tile shown in FIG. 3, but ona smaller scale and with parts broken away and showing still anotherform of base;

FIG. 12 is a section view of the base of the tile of FIG. 11 taken alongline 1212 of FIG. 11;

FIG. 13 shows the bottom plan view illustrating an assembly of tilesembodying the invention having interlocking configurations arranged topermit the tiles to be placed in staggered relation relative to eachother;

FIG. 14 is a fragmentary or perspective view of an installation of thetiles shown in FIG. 13;

FIG. 15 is a top plan View of a portion of a side edge of aninstallation of the carpet tiles shown in FIG. 3 with means for trimmingthe outer edge of said tiles and holding the outer tiles in place;

FIG. 16 is a section view taken along line 1616 of FIG. 15; and

FIG. 17 is a section view taken on line 17-17 of FIG. 15.

As shown in FIG. 1, a series of tiles 10 embodying the invent-ion may beinstalled, without the use of nails or adhesives, to form a floorcovering in which the adjoining tiles abut and are interlocked with eachother so as to present a continuous and uninterrupted surface. In suchan installation, the individual tiles may be readily shifted todifferent positions or may be replaced as desired. As illustrated, thetiles may be of different colors and be arranged to form a checkeredpattern. However, the surface design or coloring of the tiles form nopart of the present invention and are illustrated here merely to showthe adaptability of the basic structures of the tiles in differentcolors and textures to form different designs and patterns as desired.

Ti'les embodying the invention are polygonal in out line and preferablyshould have equilateral sides with corresponding interlocking elementson each side thereof so that any one side of a given tile may be fittedand interlocked with any other side of an adjoining tile or tiles. Asillustrated, the tiles will generally be square in outline.

The tiles illustrated in FIG. 1 are provided with edge structures whichinterlock when a series of the tiles are laid in abutting relationshipand in alignment, laterally or longitudinally, with respect to eachother. The tiles illustrated in FIGS. 13 and 14 are provided with edgestructures which are arranged to interlock when a series of the tilesare laid in abutting relationship with the tiles in alternate rows, inone direction, being offset or staggered with respect to the tiles inthe adjoining rows.

Tiles made in accordance with the present invention comprise severallayers, including an upper layer and a bottom layer with intermediatelayers if desired. The upper layer may be a pile fabric such as isusually used for carpeting and the bottom layer or base has interlockingconfigurations in the form of undulations extending along its side edgeswhich are shaped to engage with corresponding configurations extendingalong the side edges of adjoining tiles. If desired, intermediate layersin the form of cushioning or reinforcing material or both may beinterposed between the base and the pile fabric. It will also beunderstood that other materials, such as plastic (vinyl), rubber or thelike, may be substituted in place of the pile fabric.

Referring to FIGS. 1-4, there is a tile 10 comprising an upper layer ofpile fabric 11 of the tufted type in which the pile elements are formedon a loosely woven material 12, such as burlap, lightweight duck or thelike. The pile fabric 11 is attached to an inner layer 13 in the form ofa cushion or pad made of jute, sponge or foam rubber, foam polyurethane,or other suitable material. The pile fabric may be attached to the innerlayer by adhesives, needling or both and in some cases, such as foamrubber or a jute pad, the inner layer may be formed directly on the backof the pile fabric. The inner layer is in turn attached to a bottomlayer or base 14 by an adhesive or other suitable manner. The base maybe made of wood fibers, felted together, compressed into a board andpreferably bonded, as for example, Masonite.

The upper layer of pile fabric has straight side edges and the outerside edges 15 of the inner layer or cushion 13 are coextensive andaligned with the outer side edges of the pile fabric. The base 14 hasouter side edges 16 which extend along and undulate inwardly andoutwardly of each of the side edges 15 of the inner layer to formsimilarly shaped projections 17 extending outwardly beyond the sideedges 15 of the inner layer and alternating with similarly shapedrecesses 18 extending inwardly from the side edges of the inner layer.The projections 17 and recesses 18 are complemental to each other sothat the projections on one tile will be received snugly and conformablyin the recesses of an abutting tile to form an intermating andinterlocking connection therebetween. It will be noted that the straightside edges 15 of the inner layer are located at the mean position of theundulations forming the projections 1-7 and recesses 18 on therespective side edges of the base.

The projections 17 and recesses 18 are of arcuate shape and aredimensioned, in accordance with the present invention, so that whenthree tiles have been assembled about a given point, as shown in FIG. 2,a fourth tile may be fitted into place easily by sliding it into lockingengagement with two angularly adjacent tiles. In order to permit this,the dimensions of the projections 17 and recesses 18 must be as follows:The ratio of the chordal length A (FIG. 2) of each projection 17 alongthe axis 20 (corresponding to the edge 15 of the inner layer 13), to theheight 17 of the crest of each projection, i.e. the amplitude distanceof greatest departure of each projection 17 and each recess 18 from saidedge, must be greater than 5, i.e.

A r b Otherwise, the fourth tile cannot be slid into place withoutencountering interference from the projections on the adjoining tiles.

In the form of the tile shown in FIG. 3, which is a square tile adaptedto be installed in alignment with adjoiningtiles in two rectangulardirections (laterally or longitudinally), as shown in FIG. 1, threecomplete projections 17 and three complete recesses 18 are providedalong each side edge of the base, and the edge locking configuration onall sides of the tile are of the same shape and are uniformly arrangedso that all sides thereof are interchangeable and permit the tile to beinstalled in any desired'position with respect to adjoining tiles.

As a feature of the present invention, built-in gauge means are providedfor assuring the edge registry of the base 14 with the inner layer orcushion 13 and in turn with the top layer of pile fabric 11 inmanufacture of the tile. For this purpose, the base 14 is provided withcorners 22 having rectangular converging edges 23 located at the meanposition of the undulations and which are in registry with the edges 15of the inner layer 13 and the edges of the top layer of pile fabric. Theinterlocking undulations forming the projections and recesses extendalong the side edges of the base between the straight edges at thecorners. Thus, assembly of the square outlined layer of pile fabric 11and the square outlined inner layer or cushion 13 in accurate-registrywith the base can be readily accomplished, as for example, in a jigthrough alignment of the various layers with the square corners 22 ofthe base. Such registry assures centering of the base in relation to thepile fabric and the cushion with the interlocking configurations 17, 18on the side edges of the base 14 being properly aligned with respect tothe side edges 15 of the cushion.

While the square corners 22 of the base do not form part of theinterlocking configurations, they serve to locate such configurations,and since the region where accidental impact occurs most frequentlyduring handling is at the corners, damage to the interlockingconfigurations during such handling is avoided or at least materiallyreduced.

The dimensions of the interlocking configurations along the edges of thebase 14 may vary, but they should follow the restrictions of asexplained above. Also, the amplitude of the projections 17 and recesses18, i.e. the distance b (FIG. 2) from the edge line 15 of the innersheet 13 or axis 20 to the crests of the waves defining theseprojections and re cesses preferably should be between A" and Az. A tileof about 18" square with these dimensions has been found to beconvenient to make, store, handle and/or lay.

Specific examples of dimensions of the base 14, as applied to FIG. 2,with three full projections 17 and recesses 18 on each side as shown inFIG. 3 for a tile 18 inches square are as follows:

Corners Amplitude Chordel Rad. ll, (1, inches 11, inches length inchesAlb A, inches Va A 2. S33 5. 250 11. 332 /1 ii 2. E33 2. am 5. use A 2.S33 2. 876 7. 550

would be 5.65, which is within the limits prescribed above.

A series of tiles, constructed as described above, can be easilyinstalled or assembled by merely sliding the tiles into abuttingrelation to each other as they are laid on a floor or other surface tobe covered. When the tiles are progressively laid edge to edge inabutting alignment with each other, the projections 17 on the base 14 ofone tile extend beneath the inner layer 13 and into the recesses 18 ofthe base 14 of thenext tile. Thus, all adjoining tiles will be in matinginterlocking relationship with each other.. The square corners 22 of theassembled tiles of each group of four tiles meet in the center of thegroup, and when three tiles of such a group have been assembled, theconfiguration of the interlocking elements permits the fourthto he slideasily into position to complete the group.

As another feature of the. invention, the tile 10 is constructed so thatit is flexible enough to readily conform to any irregularities in thesurface covered by the tile and will not rock. The flexibility of thetile also permits it to be placed into or removed a space equal to orslightly greater than the width of a tile as at the outer edge of aninstallation which is bounded by a wall or between parallel rows oftiles spaced by the width of one row of tiles, where sliding of a flattile into position may not be easily accomplished. Under theseconditions, flexibility of the tile will permit the tile to be bentupwardly at its middle so as to bring the opposite edges of the tilecloser together, thereby facilitating. the removal or placement of thetile in the confined space.

It is also important where the base of the tile is made of a materialsuchas pressed bonded wood, as illustrated in FIG. 4, to prevent warpingof the base which may occur because of changing conditions of humidityor the like and which may cause the outer edges of the tile to bendupwardly and thus, render the tile unsatisfactory for use as a floorcovering. In addition, such a base will not readily conform to slightirregularities in the surface on which the tile is laid. The desiredflexibility and the prevention of warping may both be achieved in a baseof this character by scoring or cutting two series of parallclintersecting V-shaped slots 24 in criss-crossed arrangement on the outeror bottom face of the base. These crossing slots 24 are preferably deepenough to permit the base 14 to flex about these slots withoutdestroying or breaking through the remainder of the base. To beeflective for this purpose, the slots 24 may have a depth equal to about75 to 80% of the thickness of the base 14 and the thickness of the basemay be about thick.

FIG. shows a modified form of tile construction embodying the inventionin which the pile fabric 11 is attached to an inner layer 130: in theform of a scrim sheet which is flexible and which is attached to a base14a. The base 14a is similar in construction to the base 14 in FIG. 4,except that it has slots 24:: formed therein to render the base flexiblewhich are of rectangular crosssection instead of being V-shaped as theslots shown in FIG. 4. The slots 24a may also have a depth equal toabout 75-80% of the thickriess of the base 14a.

FIG. 6 shows a modified form of tile construction embodying theinvention which comprises an upper layer of pile fabric 11, a compositeintermediate layer comprising a scrim sheet 13a and a pad or cushion 13of jute, foam rubber or the like and a base 14b of material which isinherently flexible but which has sufficient struc tural integrity sothat the interlocking conformations 17 and 18 formed along its sideedges corresponding to those on the base layer 14 in the construction ofFIGS. 2, 3 and 4 will retain their conformation and serve effectivelyfor tile interlocking purposes, as described above. A material which hasbeen found to be satisfactory for this purpose is a latex saturatedpaper or cardboard, such as that manufactured by Texon, Inc., under thename of Texon and Arista. This form of material, which is customarilyused for shoe inner soles is inexpensive to manufacture, is lightweight,can be made in thin sheets, and affords the desired amount offlexibility and stifiness for the purposes of the present invention.However, when a flexible material is used for the base, slots such asare employed in the construction shown in FIG. 4, are not required.

FIGS. 7 and 8 show one form of pattern which the slots 24a in the base14a in the construction of FIG. 5 may assume. In this construction, thebase 14a is formed of one piece of pressed wood and the slots 24a followa grill or criss-crossed pattern with the number of panels defined bythe slots being shown as constituting sixteen. The tile provided with aslotted base 24a, so constructed, can be flexed about the slots 24a inany selected panel region of the tile, thereby affording greatmaneuverability in the handling of the tile.

The pattern of slots 24a in the construction of FIG. 7 may also beapplied to the base 14 of the tile shown in FIG. 4, which has theV-shaped slots 24 cut therein.

FIGS. 9 and 10 show a construction in which the base 14 of the tileshown in FIG. 4 has been sectionalized by two central gaps or cuts 25extending at right angles to each other which divide the base into fourequal square sections, each of which has slots 24 cut therein. Such anarrangement permits the tile to flex about these gaps 25 to a somewhatgreater extent than is possible with the one-piece base as shown inFIGS. 7 and 8. While the slots 24 shown in FIGS. 9 and 10 are V-shapedas in FIG. 4, it will be understood that they may be rectangular incross-section such as the slots 24a shown in FIG. 5.

FIGS. 11 and 12 show a form of tile in which the inner layer 13c and thebase 140 are both formed of pressed wood or the like. In this case, theinner layer 130 is square in shape and the pile fabric may be attachedto it either directly or through intervening layers of cushion or thelike, in edge registry there with as described above. The base 14c haslocking configurations in the form of alternate projections 17 andrecesses 18 along its edges and also has square gauge corners 22,designed and arranged to be aligned with the edge of the layer 13c asdescribed in connection with the layer 13 and base 14 of the tile shownin FIGS. 2, 3, and 4.

To impart the necessary flexibility to the layers 13c, 140, the base hasslots 24c which extend through the full thickness thereof and partiallyinto the inner layer 130, as shown in FIGS. 11 and 12. These slots mayalso be arranged in the form of a grill or criss-crossed pattern as inthe tile shown in FIG. 7.

The square corners together with the configuration of the interlockingundulations of the tiles 10 of FIGS. 1 and 3 permit such tiles to belaid only in alignment with each other in two rectangular directions.FIGS. 13 and 14 illustrate tiles ltld having interlocking undulationsand square corners which permit the tiles to be arranged, selectively,not only in alignment in two rectangular directions, as shown in FIG. 1,but also in a staggered relationship with respect to the tiles inadjoining rows of tiles. For this purpose, each side of the base 14dalong which the undulating edges extend has two duplicate complete setsof alternate projections 17d and recesses 18d which are separated by aflat space or land 26 extending along the center axis of the undulation.The lands 26 are located at the center line of the base 14d on each sidethereof in alignment with the edges 23d of the square gauge corners 22dof the base, and the length of the lands is twice the length of each ofsaid corner edges.

In the specific form of the shown in FIGS. 13 and 14, for an 18 tile,each side of the base 14 is shown with one complete projection 17d andone complete recess 18d on each side of the land 26, and each corneredge 23d is A" long while the land 26 is /2" long. Except as noted, thedimensions of the interlocking configurations 17d, 18d, would be thesame as described above in connection with FIGS. 2 and 3, with the samelimitation requiring the ratio of A/ b to be greater than 5 tofacilitate assembly in cases where the tiles are to be assembled inalignment in two rectangular directions.

For assembly in alignment in two rectangular directions, the tiles 10dof FIGS. 13 and 14 are laid as shown in FIGS. 1 and 2, and for assemblyin staggered relationship, the tiles are laid in groups of three, two ofwhich are in abutting interlocking alignment with the two corner edges23d of the two aligned tiles in end to end alignment and the third tileis placed in abutting centered interlocking relationship with the twoaligned tiles, the land 26 of this third tile abutting the alignedcorner edges 23d of the two aligned tiles.

The tiles lild of FIGS. 13 and 14, except as noted, may be constructedas described in connection with FIGS. 1-12.

If the tiles shown in FIGS. 1-14 are to be assembled to form a floorcovering for less than the full area of a room or the like, theprojections of the interlocking edge configurations may be visible andbe exposed along the outer sides of such an installation. Theseprojections, although not obtrusive enough to be unsightly, mightconstitute catches on which one may trip and the outer tiles wouldperhaps have a tendency to move out of place. In order to cover suchexposed edges and to hold the tiles in place, removable trimming meanshas been provided for installation, as shown in FIGS. 1517, along theouter edges of such an installation to cover and protect theprojections. Such trimming means comprises a strip 36) in the form of amolding made of wood, metal or plastic by molding, extrusion orotherwise and which has a conformation adapted to mate and interlockwith the edge interlocking conformations of the tiles on the outer edgesof the installation. The molding strip 30 has an upper straight edge 31on its inner side and on its lower inner side is formed with astrip-like tile interlocking section 3 2, which has its inner edge 33centered with respect to the molding edge 31 and undulated to correspondto the undulations of the edge of the base 14 of the tile 10 to providealternate projections 34 and recesses 35, corresponding in, size andshape to the alternate projections 17 and recesses 13 of the tiles andconnecting lands 36 along the center of the undulations between groupsof such alternate. projections 34 and recesses 35, each groupcorresponding to the. group of alternate projections 17 and recesses 18on each side of the tile. With the inner edge 31 of the molding strip 30abutting the straight edge of the inner sheet 13 of the tile, theprojections 34 and recesses 35 on the strip mate interlockably with theprojections 17 and recesses 18 on the tile. Since it is desirable toprovide molding strips 30 longer than the length of a tile; i.e., tospan a number of tiles, the land 36 on the strip is twice as long as theedges 23 of the corners 22 of the individual tiles so as to extend alongthe full length of and in conforming abutment with two of such corneredges of adjoining sides tiles where the molding strip 30 extends acrossthe juncture of two tiles.

The tile interlocking part 32 of the strip 30 has been referred to as astrip-like section because this section in effect is like a fiat strip.Although this strip-like section is shown in the drawings as an integralpart of the strip 30, it may very well be a separate strip fitted into alower inner recess of the main body of the strip and secured thereto, asfor example by screws, adhesive or the like.

Also, although the strip 30 shown is designed to fit the type of tileshown in FIGS. 1-4 and may be easily designed to fit the type of tileshown in FIGS. -12, it can be easily designed according to theprinciples illustrated in FIGS. -17 and previously described, to fit thetype of tile shown in FIGS. 13 and 14. In that case, the interlockingsection of the molding strip is designed with locking configurationscorresponding to those on the tile 10d of FIGS. 13 and 14, with landsfor abutting conformance with the intermediate lands 26 of the tiles andlands for abutting conformance with the corner edges 23 of adjoiningtiles.

The molding strip 30 may, if desired, be held down to a surface or otherflooring by easily removable nails 38. The molding strip 30 whenapplied, not only trims the sides of the rug and protects theinterlocking configurations of the tiles or outer sides of theinstallation, but it also holds the assembled tiles against movement.

The carpet tiles of the present invention can be used in differentcolors or textures to produce different rug patterns or designs, can beeasily stored and/ or shipped, can be easily laid, can be easilyreplaced when worn or stained and can be interchanged in a rug, forexample, tiles may be interchanged between places where they have becomeworn and are in full view and places which are subjected to littletraffic, which are not prominent and which consequently have tiles inbetter condition.

While the invention has been described with particular reference tovarious embodiments illustrated herein, it is to be understood that itis not to be limited thereto but is to be construed broadly andrestricted solely by the scope of the appended claims.

We claim:

1. A floor carpet tile comprising a plurality of layers of generallyquadrilateral shape, said layers being joined together to form a unitincluding a square upper layer comprising a carpet fabric presenting awalking surface and a base layer underlying said upper layer, said upperlayer having straight side edges for abutting opposing side edges ofadjoining tiles, said base layer having undulations extending along eachof the side edges thereof for interlocking with correspondingundulations on an adjoining tile, said undulations forming curvedprojections and recesses of complementary shape, respectively extendingalternately beyond and beneath the upper layer along the straight side.edges thereof with said straight edges centered with respect to thecorresponding undulations, the ratio of the width of said projectionsand recesses as measured along said straight edges to the maximumamplitude thereof as measured from said straight edges being greaterthan five, the conformations of the edges of said base layer beingsimilar on all sides, whereby any one side of the tile may be fitted andinterlocked with any side of an adjoining similar tile in a floorcovering installation.

2. A floor tile as defined in claim 1 wherein the undulations formingthe projections and recesses along the side edges of the base layerperiodically terminate in straight lines which are aligned with thestraight side edges of the upper layer.

3. A floor tile as described in claim 1 wherein the undulations formingthe projections and recesses along the edges of the base layer terminatein straight lines which are disposed at right angles to each other atthe corners of the base layer and which are aligned with the straightside edges of the upper layer at the corners thereof.

4. A floor tile as described in claim 3 wherein the undulations alongthe edges of the base layer also terminate in straight lines at pointsintermediate the ends of said side edges, the last-mentioned straightlines being aligned with the straight edges of the upper layer and beingtwice as long as the straight lines at the corners of the base.

5. A floor tile as described in claim 1 wherein the base layer is formedof a flexible material.

6. A fioor tile comprising a plurality of layers of generallyquadrilateral shape, said layers being joined together to form a unitincluding a square upper layer presenting a walking surface and a baselayer underlying said upper layer, said upper layer having straight sideedges for abutting opposing side edges of adjoining tiles, said baselayer having undulations extending along each of the side edges thereoffor interlocking with corresponding undulations on an adjoining tile,said undulations forming curved projections and recesses ofcomplementary shape, respec' tively extending alternately beyond andbeneath the upper layer along the straight side edges thereof with saidstraight edges centered with respect to the corresponding undulations,the ratio of the width of said projections and recesses as measuredalong said straight edges to the maximum amplitude thereof as measuredfrom said straight edges being greater than five, the conformations ofthe edges of said base layer being similar on all sides, whereby any oneside of the tile may be fitted and interlocked with any side of anadjoining similar tile in a floor covering installation.

7. A floor tile as described in claim 6, wherein the undulations formingthe projections and recesses along the edges of the base layer terminatein straight lines which are disposed at right angles to each other atthe corners of the base layer and which are aligned with the straightside edges of the upper layer at the corners thereof.

References Cited in the file of this patent UNITED STATES PATENTS Re.16,867 Healy Feb. 7, 1928 Re. 17,020 Healy July 3, 1928 1,657,159Greenebaum Jan. 24, 1928 1,796,973 Wright Mar. 17, 1931 1,808,591 BruceJune 2, 1931 2,175,698 Netz Oct. 10, 1939 2,293,751 May Aug. 25, 19422,758,044 Terry Aug. 7, 1956 3,001,902 Cooke et a1 Sept. 26, 1961FOREIGN PATENTS 647,024 Great Britain Dec. 6, 1950 562,724 Canada Sept.2, 1958

1. A FLOOR CARPET TILE COMPRISING A PLURALITY OF LAYERS OF GENERALLYQUADRILATERAL SHAPE, SAID LAYERS BEING JOINED TOGETHER TO FORM A UNITINCLUDING A SQUARE UPPER LAYER COMPRISING A CARPET FABRIC PRESENTING AWALKING SURFACE AND A BASE LAYER UNDERLYING SAID UPPER LAYER, SAID UPPERLAYER HAVING STRAIGHT SIDE EDGES FOR ABUTTING OPPOSING SIDE EDGES OFADJOINING TILES, SAID BASE LAYER HAVING UNDULATIONS EXTENDING ALONG EACHOF THE SIDE EDGES THEREOF FOR INTERLOCKING WITH CORRESPONDINGUNDULATIONS ON AN ADJOINING TILE, SAID UNDULATIONS FORMING CURVEDPROJECTIONS AND RECESSES OF COMPLEMENTARY SHAPE, RESPECTIVELY EXTENDINGALTERNATELY BEYOND AND BENEATH THE UPPER LAYER ALONG THE STRAIGHT SIDEEDGES THEREOF WITH SAID STRAIGHT EDGES CENTERED WITH RESPECT TO THECORRESPONDING UNDULATIONS, THE RATIO OF THE WIDTH OF SAID PROJECTIONSAND RECESSES AS MEASURED ALONG SAID STRAIGHT EDGES TO THE MAXIMUMAMPLITUDE THEREOF AS MEASURED FROM SAID STRAIGHT EDGES BEING GREATERTHAN FIVE, THE CONFORMATIONS OF THE EDGES OF SAID BASE LAYER BEINGSIMILAR ON ALL SIDES, WHEREBY ANY ONE SIDE OF THE TILE MAY BE FITTED ANDINTERLOCKED WITH ANY SIDE OF AN ADJOINING SIMILAR TILE IN A FLOORCOVERING INSTALLATION.